化学三重表征的界定及其关系分析

化学三重表征具有内部表征和外部表征两重含义。从外部表征看,化学三重表征是指化学宏观世界、微观世界和符号世界知识的外在呈现形式;从内部表征看,化学三重表征是指这3种水平的知识在个体头脑中的加工和呈现形式。三重表征是一个互有联系的整体,对化学学习具有重要意义。     

三重表征视域下的化学学习研究考查

梳理了三重表征研究范式下部分化学学习研究成果。基于三重表征,研究者细致考查学生在宏观表征、微观表征和符号表征等单维度化学学习中遇到的困难;结合信息加工模型,解释了化学学习机制,形成对化学学习的动态认识,指出以上研究中尚待完善之处,以期为化学学习的深入研究提供借鉴。     

化学三重表征的研究与展望*——基于CiteSpace的可视化分析

基于CiteSpace软件,运用知识图谱、关键词聚类分析等方法,分析国内化学三重表征领域的研究现状和前沿热点,将信息可视化,为我国学者进一步完善化学三重表征的研究提供帮助和借鉴。放眼于国际科学教育的趋势和我国化学核心素养的落地,期望将“化学三重表征”思维方式及策略嵌入日常的教学,成为化学课堂教学的未来景观。     

化学学习中"宏观-微观-符号"三重表征的研究

“宏观-微观-符号”三重表征是体现化学学科特征的思维方式,能增进学生对化学知识的理解。本研究在对三重表征思维方式进行分析的基础上,采用问卷调查的方法,对不同群体学生化学学习三重表征水平进行了探查和分析,为化学教学提供了一个新的视角。     

基于SOLO理论的思维导图建构三重表征整体关系的教学研究

以氯水的教学为案例,运用三重表征方式多元角度认识和理解物质,并用思维导图直观表示三重表征之间的联系。研究结果表明,SOLO分类理论可有效指导教师确定学生的学习最近发展区及有效的教学策略;运用思维导图可直观表示化学知识三重表征之间的逻辑关系,促进学生建构起三重表征的有机整体关系,加速以符号表征为桥梁进行三重表征之间的互译转换,促使学生将多点知识结构发展为关联知识结构、抽象拓展结构水平。因此,在教学中应用思维导图建构化学三重表征的整体关系,有利于提高学生学习结果的质量。     

化学微观表征的方法与教学策略

将化学宏观现象进行形象、直观与动态的微观表征,能激发学生的学习兴趣,协助学生理解化学原理与规律。在几种不同形式的微观表征方法中,微观表征图能有效地消除相异构想,是建构化学三重表征的突破口,有利于化学三重表征的转化与融合。     

初三学生化学三重表征转化的眼动实验研究

化学三重表征研究一直深受国内外学者的重视,目前,初级表征的研究已有一定的理论基础,但是,次级表征（即不同表征水平之间的转化）的研究仍是研究的弱点和难点。纸笔检测、口语报告研究方法都存在一定的局限。为了从信息加工过程研究三重表征间转化的基本特点,采用眼动分析法对12名初三学生进行3×3两因素混合实验。结果显示：（1）在初三上册期末,学优生基本可以进行三重表征之间的直接转化;（2）学中生符号表征较强且依赖于符号表征,表现出“双通道协同加工”现象,符号—宏观、微观转化水平较强,宏观—微观、符号和微观—符号、宏观转化水平较弱;（3）学困生普遍缺乏三重表征的思维和意识,三重表征间的转化水平较低,相比较而言,符号-宏观、微观表征转化稍强于宏观-微观、符号表征转化和微观-符号、宏观表征转化。     

化学知识三重表征的话语意义探析*

基于科学哲学和语言学理论,强调化学学科中的三重表征的话语意义,旨在帮助学生将头脑中的三重表征思维用语言科学地表达出来并进行社会性交往。在明确三重表征与话语的关系的基础上,借助于相关教学片段,对三重表征的话语意义(语法学、语义学和语用学意义)进行探析,将宏观微观符号表征中各自的语言内部联系以及彼此间的话语表达关系解构出来,从而全面提升学生在建构、关联及转换表征过程中的交往效率。最后针对相关教学问题,提出了3条教学策略。     

朝鲜族高中生化学三重表征转换能力的调查研究

利用多维分析系统（MAS）,采用2段式问卷并结合课堂观察,以普通高中物质结构与性质模块为内容,调查了延边地区朝鲜族高中生化学三重表征转换能力及其影响因素。结果表明：朝鲜族高中生化学三重表征转换能力由高到低依次为宏观-微观相互转换能力 、宏观-符号相互转换能力、微观-符号相互转换能力。     

含芴共轭高分子的合成、表征及性能研究——推荐一个高分子化学综合实验

推荐了一个高分子化学综合实验——含芴共轭高分子的合成、表征及性能研究。实验内容包括利用Sonogashira偶联反应合成共轭高分子,采用核磁共振和红外光谱等检测手段对其结构进行表征,并利用紫外-可见光谱、荧光和热重分析对其性能进行研究。本实验结合了高分子化学和聚合物仪器分析与表征的知识点,建议纳入高分子专业高年级综合实验课程。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.